Photosensitive coating containing a hydrophilic colloid and a polyvinyl chloride dispersion



Patented Apr. 13, 1954 HYDROPHILIC COLLOID AND VINYL CHLORIDE DISPERSIONA POLY- Henry C. Staehle and Lawrence E. Martinson,

New Jersey Rochester, N. Y.,. asslgnors to Eastman Kodak Company,Rochester, N. Y., a corporation of No Drawing. Application December 13,1949, Serial No. 132,795

Claims. 1

This invention relates to the preparation of photographic resistmaterials and to methods of forming images therein.

In Staehle U. S. patent-application Serial No. 558,346, filed October12, 1944, now abandoned, of which U. S. Patent 2,604,388 is acontinuationin-part, a light-sensitive material is described which maybe used as a photosensitive resist. The material consists of abichromated hydrophilic colloid such as gelatin or glue containing anaqueous colloidal dispersion of a soft, synthetic resin which dries to acontinuous film when the aqueous dispersion alone is coated on glass.The sensitive material may contain a pigment such as titanium oxide andwith or without the pigment when coated on a support. and processed toform a photographic relief image, it may be used as a resist for etchingwith a light sand blast or with acid or alkali or electrolytically.

We have found that a satisfactory resist material, particularly foretching, may be prepared by replacing the dispersion of soft, syntheticresin of the sensitive material described in Patent 2,604,388, witheither saran latex or an aqueous colloidal dispersion of polyvinylchloride-polyvinyl acetate copolymer or by adding either the saran latexor dispersion of polyvinyl chloride polyvinyl acetate copolymer to thesensitive material containing the. dispersion of soft, synthetic resin.The sensitive material thus produced may be processed in the mannerdescribed in Patent 2,604,388 to form a relief image; the image afterprocessing is extremely resistant to acids and alkalis and is especiallysuitable for use as an etching resist. Saran latex is a dispersion inwater of polyvinylidine chloride and about 20% of the weight ofpolyvinylidine chloride of dibutyl phthalate as a plasticizer. Materialof this type is described in U. S. Patents 2,333,633- 4-5.

The resist materials of our invention may be applied to supports ofglass, synthetic resin, cellulose ester, steel, aluminum, etc., but areparticularly useful for application to anodized aluminum, to which veryfew photographic sensitive resists may be satisfactorily applied. Ourcomposition adheres well to any cleansurface although in some cases itmay be desirable to coat the support with a primer before application ofthe resist materials. Primers which may be used include turpentine,cumarone resins, alkyd resins, plasticized cellulose nitrate, oxidizeddryingoils, chlorinated rubber, etc. i

The sensitive materialsof our invention or 2 made by mixing either saranlatex or the dispersion of polyvinyl chloride-polyvinyl acetatecopolymer with a hydrophilic colloid such as gelatin or glue andsensitizing the mixture with a bichromate such as ammonium bichromate.The saran latex or dispersion of polyvinyl chloride-polyvinylacetatecopolymer may be used alone in the sensitive composition or usedtogether with an aqueous dispersion of a soft, synthetic resin, such aspolymethyl acrylate or polyethyl acrylate or mixture, of these resins.When used either alone or in admixture, with a dispersion of theacrylate resin, thesensitive material containing the saran latexproduces a light sensitivecomposition,which may be coated on thesupports mentioned above, exposed to an object or image and developed bywashing with water. The exposed portions of the coating wash away thusroducing a direct positive image.

Our invention will be illustrated by reference to the followingexamples.

Example 1 A sensitive composition was made by adding 10 grams of gelatindissolved in 20 cc. of water to 40 cc. of saran latex diluted with 20cc. of water and then adding 5 cc. of 20% ammonium bichromate solutionand 10 cc. of a 5% solution of as a wetting or spreading agent. Thegelatin used in the composition was a lime-process gelatin highlyhydrolyzed during manufacture. This gelatin has a low viscosity and isreferred to as "low grade gelatin. The saran latex used in thecomposition had a solids content of about Example 2 A sensitivecomposition containing both saran latex and an aqueous dispersion ofpolymethyl acrylate or polyethyl acrylate resin was made by mixing inorder the following solutions.

A. Gelatin grams Water cc 690 Sodium phosphate "grams" 10 B. Polymethylacrylate or polyethyl acrylate dispersion cc 490 Saran latex cc 400 C.Water cc 1130 Potassium chromate grams 2 1 Ammonium bichromate (20%solution) cc 35 NaI-E04-7H2O grams 5 Ammonium acetate- "grams" 40 3 Thiscomposition when coated in the usual manner was exposed under an imageand processed with water and then heated to 130 C. to heat seal theresin. It was successfully used as an etching resist.

Example 3 A sensitive composition was madeby mixing in order thefollowing solutions:

A. Gelatin grams 120 Water cc 400 B. Water 7 cc 400' Ethyl Cellosolve cc20 Saran latex cc 500 C. Water 1 7 c 250 ;:H21CON-C1H4SO3NB' grams 10Ammonium nitrate grams 10 Ammonium hydroxide (28% solution) cc '15Ammonium bichromate (20% solution) Example 4 V Asensitive compositionwas made by adding the following solution A to solution B, and thenadding 0 to AB:

A. Gelatin "grams" I 250 Water c 880 A m m o n i u m I bichromate (20%solution) cc 150 B. Water cc 500 Triton 720 (sodium salt of alkylatedaryl polyether sulfonate) cc 40 Geonf 31-X (dispersion of polyvinylchloride-polyvinyl acetate oopoly- The composition was coated in theusual manner, exposed to an image, processed with water, and heated toabout 120 C. for 5 minutes to set the resin. It was used successfully asan etching resist.

As in the case of the sensitive material of U. S. Patent 2,604,388, theresist composition of the present invention may be handled in ordinaryroom light for a reasonable length of time without fog. The material asdescribed in Example 2 when coated on a suitable support will produce animage of satisfactory density and contrast when exposed to a l50-wattmercury vapor lamp for 15 seconds at a distance of about inches.Exposure to ordinary direct sunlight forabout the same length of timewill also produce a satisfactory image. a

Development is carried out by immersing in,

or spraying the exposed material with, water. In most cases, water aloneis satisfactory although it may be desirable to add a hardening agentsuch as alum, a swelling agent such as ammonium hydroxide oran acid orsolvent to the water.

After exposure, development and drying the images produced according toour invention are light-stable and resistant to ordinary handling. Theymay be removed from the support by the use of abrasives or solvents butdo not peel readily once they have become dry. V

The sensitive materialof our invention contains approximately two partsof resin to one part of gelatin or glue and since the resin has highresistance to alkalies and acids, the resulting image is extremelydurable. Not only does it confer excellent protection to hydrochloricacid but the photographic image has high resolution as well. This isimportant in making half tone images, which is one of the uses to whichour material is adapted. Half-tone images etched in anodized aluminumcan be made from 300-line half-tone positives. Anodized aluminum may besatisfactorily .etchedwith our resist material and halftone images orany plates of exceptional fine detail can be prepared easily andquickly. Another field'of usefulness is in making relief printing platesinasmuch as the anodized layer of aluminum has exceptional wearresistance. A third application is in making planographic printingplates in which a very shallow etch is all that is required.

It will be understood that thejexamples and modifications includedherein are illustrative only.

We claim:

1. A light-sensitive coating composition comprising a mixture of abichromated gelatin, an aqueous dispersion of a resin selected from theclass consisting of polyvinylidene chloride latex and polyvinylchloride-polyvinyl acetate copolymers, the ratio of said gelatin to saidaqueous dispersion being between about 1 to 2.5 and 1 to 5, saidcomposition being adapted to produce a light-sensitive coating in whicha reversal image can be formed by exposure to light and development inan aqueous solution.

2. A light-sensitive coating composition comprising a mixture of abichromated gelatin, an aqueous dispersion of a polyvinylidene chloridelatex, an aqueous colloidal dispersion of awaterinsoluble, soft,acrylate resin, the ratio of said gelatin to said aqueous dispersionsbeing between about 1 to 2.5 and l to 5, said composition being adaptedto produce a light-sensitive coating in which a reversal image can beformed by exposure to light and development in an aqueous solution.

3. The method of making a photographic relief image suitable as anetching resist, which comprises coating a support which can be etched,with a mixture of a bichromated gelatin, and an aqueous dispersion of apolyvinylidene chloride latex, theratio of said gelatin to said aqueousdispersion being between about 1 to 2.5 and 1 to 5,

prises coating .a support which can be etched,

with a mixture of a bichromated gelatin, an aqueous colloidal dispersionof a soft, acrylate resin, and an aqueous dispersion of a polyvinylidenechloride latex, the ratio of said gelatin to said aqueousdispersions-being between about 1 to 2.5

and l to 5, drying said coating, exposingit to an image, and washingaway the exposed portions of said coating with an aqueous solution toleave said coating in the unexposed portions. q 7

5. Asensitive photographic resist material come prising an -etchablesupport having thereon a mixture of bichromated gelatin, an aqueous dis,

persion of a polyvinylidene chloride latex, and an aqueous colloidaldispersion of aresin-of the group consisting of 'polymethyl acrylate andpolyethyl acrylate and mixtures thereof, the ratio 5 of said gelatin tosaid aqueous dispersions being FOREIGN PATENTS between about 1 to 2.5and 1 to 5. Number Country Date References Cited in the file of thispatent 573371 Great Bmam 1945 UNITED STATES PATENTS a Om i 1 f Z Z SiZIn t w. c a lges o. 0v. ,0 ves igai ggg a i g 1 tion of Aqueous Acrysol,Geon and Saran Dis- 1,981,102 Hagedorn et a1 Nov. 20, 1934 31 9 2016,490 Fikentscher Oct 8 1935 Vmyhciene ChlOIldB Polymer, Gpgg n eta1., 2099 297 Clement 16 1937 10 A08 meeting, March 18, 1942, AtlanticClty, N. J 2,500,028 Griggs et a1 Mar. 7, 1950 2 and 4 clted' 2,533,530Staehle Dec. 12, 1950

1. A LIGHT-SENSITIVE COATING COMPOSITION COMPRISING A MIXTURE OF ABICHROMATED GELATIN, AN AQUEOUS DISPERSION OF A RESIN SELECTED FROM THECLASS CONSISTING OF POLYVINYLIDENE CHLORIDE LATEX AND POLYVINYLCHLORIDE-POLYVINYL ACETATE COPOLYMERS, THE RATIO OF SAID GELATIN TO SAIDAQUEOUS DISPERSION BEING BETWEEN ABOUT 1 TO 2.5 AND 1 TO 5, SAIDCOMPOSITION BEING ADAPTED TO PRODUCE A LIGHT-SENSITIVE COATING IN WHICHA REVERSAL IMAGE CAN BE FORMED BY EXPOSURE TO LIGHT AND DEVELOPMENT INAN AQUEOUS SOLUTION.